Some contemporary computing devices use two air moving devices (fans) to cool the various circuitry of the device. Typical computing devices use high-frequency pulse-width modulation controlled fans, in which each fan's operation is controlled by signals on a frequency control line sent from a controller component on the motherboard. Traditional high-frequency pulse-width modulation controlled fans are each driven by four total control lines, including the aforementioned controller-driven frequency control line, a control line for power (e.g., positive voltage), a control line for ground, and a tachometer line used for sensing rotational speed to check whether the fan is functioning properly.
In general, computer system designers aim to design smaller, more powerful computing devices at a lower cost. Any technology that consumes less computer motherboard space typically helps in board routing and the design of smaller and/or more computing devices that are more powerful/have more features. Further, any reduction in the number of components typically helps to lower the per-device cost. Thus, it is generally desirable to have fan technology that helps accomplish one or more of these aims.